The invention relates to clamp connector assemblies for forming releasable electrical connections between contact pads on circuit members. The circuit members may be rigid, such as circuit boards or substrates or flexible, such as ribbon cables.
Clamp connector assemblies for forming releasable connections between flexible and rigid circuit members are well known. The assemblies conventionally include a clamp and an elastomer pad. The clamp biases two circuit members together to form electrical connections between pairs of contact pads on the circuit members. A flexible circuit member may directly overly a rigid or flexible circuit member so that the pads on the circuit members contact each other. An elastomer pad overlying the flexible circuit member is compressed to form the electrical connections. Alternatively, the circuit members may he located on opposite sides of an interposer assembly which is compressed by the clamp to form electrical connections between opposed pairs of contact pads. The interposer assembly may include elastomer pads. Clamp connector assemblies form electrical connections between two circuit boards, a circuit board and a flexible circuit member or two flexible circuit members.
Conventional clamp connectors have a bottom plate, a pair of retention posts extending upwardly from the bottom plate, a top plate and a mechanism engaging the ends of the posts to move the top plate toward the bottom plate to form electrical connections between circuit members held between the plates. The circuit members, and an interposer assembly, if used, are clamped between the two plates. Threaded screw type closing mechanisms typically move the top plate toward the bottom plate, clamp the two circuit members together and form desired electrical connections.
Modern circuit elements have very densely spaced contact pads. Connector assemblies for forming connections between the assemblies are correspondingly small, yet require relatively high contact pressure in order to assure a sufficient contact force is applied to each pair of contact pads on the circuit members to form reliable electrical connections. This means that relatively high force is required to form the electrical connections. Manual actuation of the clamp is difficult due to the small size of the assemblies and the relatively high actuation forces required. Further, uniform contact pressure must be maintained at each pair of contact pads on the circuit members. The pads are spaced on the surfaces of the circuit members, conventionally in side-by-side rows. In order to assure uniform pressure connections, the clamp used to hold the circuit members together must provide uniform contact pressure to each of the large number of contact pad pairs independent of the location of the contact pads on the circuit members.
The contact pressure required to close conventional clamp assemblies to form electrical connections may be provided by two threaded members engaging two retention posts. Simultaneous manual engagement of threaded members is difficult, particularly where high torque is required to rotate threaded members to form the electrical connections.
Conventional clamp connector assemblies for forming connections between contact pads on a flexible circuit member, typically a ribbon cable, and contact pads on a rigid circuit member, typically a circuit board, include a clamp and a housing joined to a flexible circuit member with an elastomer pad held between the housing and the flexible circuit member. When the assembly is closed, the elastomer pad biases contact pads on the flexible circuit member away from the housing against contact pads on the rigid circuit member to form electrical connections. Manufacture of this type of clamp connector assembly is facilitated by making a subassembly including the housing, elastomer pad, and the flexible circuit member with the circuit member permanently mounted to the bottom of the housing and the pad is confined in a recess in the housing between the circuit member and the plate. The subassembly, together with a bottom plate and retention posts, elastomer mat and clamp members, is shipped to an end user for mounting on a rigid circuit member with bottom plate and mat on the lower side of the rigid circuit member, the retention posts extending through holes in the rigid circuit member and the subassembly and the clamp members engaging the upper ends of the retention posts to compress the elastomer pad, bias the flexible circuit member against the rigid circuit member and form the electrical connections.
It is important that the flexible circuit member be maintained in a flat, planar position on the housing in the subassembly. Outward bowing of the flexible circuit member overlying the elastomer pad produces undesired ripples in the flexible circuit member. The ripples extend along the flexible circuit member an appreciable distance away from the subassembly and can stress the member and prevent proper routing of the member. Rippling of the flexible member in the subassembly occurs because the uncompressed elastomer pad has a thickness greater than the depth of the recess in the housing and extends out of the housing and pushes or bows the flexible circuit member outwardly from the desired flat portion overlying the housing.
Therefore, there is a need for an improved manually closed clamp connector assembly for forming electrical connections between circuit members. The clamp assembly should be easily closed and opened by an operator yet assure reliable pressure electrical connections between large numbers of opposed pairs of contact pads. After closing, the assembly should be compact without the closing mechanism extending beyond the perimeter of the assembly.
There is also a need for an improved clamp connector assembly for forming connections between a flexible circuit member and another circuit member where the assembly simultaneously forms a large number of electrical connections by pressing an elastomer pad against the flexible circuit member without distortion of the flexible circuitry before or during clamping.
The invention is an improved clamp connector assembly for forming electrical connections between two circuit members. The circuit members may be rigid or flexible. Two connector assemblies are disclosed. A first embodiment clamp connector assembly includes an interposer and forms electrical connections between two rigid or flexible circuit members. The second embodiment clamp connector assembly forms electrical connections between a first flexible circuit member and a second circuit member, which may be rigid or flexible.
Both connector assembly embodiments include an improved manual clamp in which the circuit members to be joined are positioned between a bottom plate and a top plate and manually rotatable clamp members are fitted on the ends of retention posts extending up from a bottom plate and through holes in a top plate. The clamp members include elongate, offset and force multiplying arms extending from opposite sides of the top plate. The arms are manually rotated to closed, compact positions overlying the top of the top plate. Rotation of the arms cams the top plate toward the bottom plate to sandwich the circuit members between the plates and form electrical connections between pads on the two circuit members. During and following clamping, the top plate is maintained parallel to the bottom plate to assure uniform contact pressure is exerted on all pairs of contact pads. The clamp members are easily mounted on and removed from the retention posts.
In the first embodiment clamp connector assembly, the two circuit members are mounted on the retention posts with an interposer assembly positioned between the members. The interposer assembly is resilient to assure proper pressure electrical connections are formed between contacts on opposite sides of the assembly and contact pads on the circuit members.
In the second embodiment clamp connector assembly, a flexible circuit member is positioned on top of contact pads on a rigid or flexible circuit member and a housing is positioned on top of the flexible circuit. The housing carries an elastomer pad overlying the contacts on the flexible circuit member. The two circuit members and the housing are positioned between the clamp top plate and bottom plate. Manual clamp members are attached to the ends of the retention posts extending above the top plate and then rotated to cam the top plate toward the bottom plate to form the desired electrical connections.
The second embodiment assembly includes a subassembly including the flexible circuit member, the housing, the elastomer pad and the top plate. The subassembly may be manufactured as a unit for shipment to the user together with the remaining parts of the second embodiment assembly. During manufacture, the flexible circuit member is permanently mounted on the housing flat, without ripples, and the pad and top plate are mounted in the-housing. The top plate and pad are loosely confined in the housing so that the pad does not flex the flat flexible circuit.
Both connector assembly embodiments form reliable electrical connections between a large number of contact pads on two circuit members. These connections are readily releasable by manually rotating the cam members back to the initial positions, with the arms extending outwardly from the top plate. When in this position, the two circuit members may be disengaged by removing the components of the assembly from the retention posts extending from the bottom plate.
Other objects and features of the invention will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings illustrating the invention, of which there are seven sheets of drawings and two embodiments are disclosed.